Technical Field
The present invention relates to preparation of size-controlled ultra-small surface-modified iron-based metal oxide nanoparticles, nanocolloids containing such nanoparticles, and methods of producing such nanoparticles for applications that require nanoparticles with advantageous magnetic properties.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Metal oxide nanoparticles have been produced through various synthetic methods such as basic aqueous co-precipitation, sol-gel, microemulsion, sonochemical processes, thermal decomposition of organometallic precursors and reduction of metal ions at elevated temperatures [M. H. El-Dakdouki, K. El-Boubbou, J. Xia, H. Kavunja, X. Huang, Chemistry of Bioconjugates, 281-314, John Wiley & Sons, 2014; A.-H. Lu, E. L. Salabas, F. Schüth, Angewandte Chemie International Edition, 46, 8, 1222-1244, 2007; S. Sun, C. B. Murray, D. Weller, L. Folks, A. Moser, Science, 287, 5460, 1989-1992, 2000; N. Lee, T. Hyeon, Chemical Society Reviews, 41, 2575-2589, 2012; Jun, Y.-w.; Lee, J.-H.; Cheon, J., Angewandte Chemie International Edition, 47, 5122-5135, 2008; Wahajuddin, M.; Arora, S., International Journal of Nanomedicine, 7, 3445-3471, 2012—each incorporated herein by reference in its entirety]. Among these methods, thermal decomposition of organometallic compounds in high boiling point, nonpolar organic solvents has been the most attractive route to synthesize monodisperse nanocrystals and to afford control over the size of the nanocrystals [C. B. Murray, S. Sun, U.S. Pat. No. 6,262,129; S. Sun, C. B. Murray, D. Weller, L. Folks, A. Moser, Science, 287, 5460, 1989-1992, 2000; S. Sun, H. Zeng, Journal of the American Chemical Society, 124, 28, 8204-8205, 2002; S. Sun, H. Zeng, D. B. Robinson, S. Raoux, P. M. Rice, S. X. Wang, G. Li, Journal of the American Chemical Society, 126, 1, 273-279, 2004; J. Park, K. An, Y. Hwang, J.-G. Park, H.-J. Noh; J.-Y. Kim, J.-H. Park, N.-M. Hwang, T. Hyeon, Nature Materials, 3, 12, 891-895, 2004; N. R. Jana, Y. Chen, X. Peng, Chemistry of Materials, 16, 20, 3931-3935, 2004; Yu, W. W.; Falkner, J. C.; Yavuz, C. T.; Colvin, V. L., Chemical Communications, 2306-2307, 2004; K. Abdulwahab, M. A. Malik, P. O'Brien et al., Dalton Transactions, 42, 1, 196-206, 2013—each incorporated herein by reference in its entirety]. Another strategy is “hot-injection” by rapid introduction of reagents into the hot solution (≥300° C.) containing the surfactants [Frey, N. A.; Peng, S.; Cheng, K.; Sun, S., Chemical Society Reviews, 38, 9, 2532-2542, 2009]. However, the production of the metal oxide nanoparticles according to the above thermolysis methods has problems and limitations. First, it is necessary to heat the reaction mixture to very high temperatures, for example up to 360° C., which requires highly trained personnel and is dangerous in practice. Moreover, the use of expensive polyalcohol components as the reducing agent causes many side reactions that lead to polyaldehydes and polyorganic acids, resulting in difficult byproduct separations. The production cost of the metal oxide nanoparticles is high, because many expensive reactants, such as 1,2-hexanediol, are added. More importantly, the use of high temperature reactions is, in practice, dangerous and limits the choice of the nanoparticle capping agents. No polymers can be used and the obtained hydrophobically-coated nanoparticulate products can be only dispersed in organic solvents. In the method of rapid “hot-injection”, a complicated process of synthesizing and purifying the metal precursor must be implemented, making it difficult to synthesize uniform nanoparticles in great quantity, and a complicated process must be conducted in order to precisely control the reaction conditions, reducing the reaction efficiency. The above methods has limited applications in the industry and usually produces nanocrystals with low magnetization [Y. Lee et al., Advanced Functional Materials, 15, 503-509, 2005; J. Ge, Y. Hu, M. Biasini, W. P. Beyermann, Y. Yin, Angewandte Chemie International Edition, 46, 23, 4342-4345, 2007—each incorporated herein by reference in its entirety].
Synthesizing metal oxide nanoparticles by precipitation in aqueous solutions does not require high temperatures and may involve simple manufacturing steps. However, synthesizing metal oxide nanoparticles by Massart's aqueous basic co-precipitation of metallic salts in water often lead to agglomerated nanoparticles, regardless of whether the co-precipitation is performed in the presence or absence of stabilizers and/or surfactants, and the size of the nanoparticles cannot be controlled [R. Massart, IEEE Transactions on Magnetics, 17, 2, 1247-1248, 1981; M. Mandavi et al., Molecules, 18, 7, 7533-7548, 2013; J. S. Basuki, A. Jacquemin, L. Esser, Y. Li, C. Boyer, T. P. Davis, Polymer Chemistry, 5, 7, 2611-2620, 2014; X. Gu, Y. Zhang, H. Sun, X. Song, C. Fu, P. Dong, Journal of Nanomaterials, 2015, Article ID 154592, 12 pages, 2015; Y. Lee et al., Advanced Functional Materials, 15, 503-509, 2005; Kamat, M., El-Boubbou, K., Zhu, D. C., Lansdell, T., Lu, X., Li, W., Huang, X., Bioconjugate Chemistry, 21, 2128-2135, 2010; Palmacci, S.; Josephson, L.; Groman, E. V. Patent WO9505669A1, 1995; Tassa, C.; Shaw, S. Y.; Weissleder, R., Accounts of Chemical Reseacrch, 44, 842-852, 2011; B. L. Cushing, V. L. Kolesnichenko, C. J. O'Connor, Chemical Reviews, 104, 9, 3893-3946, 2004—each incorporated herein by reference in its entirety]. In general, there are difficulties in achieving colloidal nanoparticles with narrow size distributions using wet chemical synthesis in aqueous solutions, regardless of whether the stabilizer is added during or after the precipitation of metal oxide nanocrystals [Hasegawa M., Hokukoku S., U.S. Pat. No. 4,101,435; Kresse M., Pfefferer D., Lawaczeck R., Wagner S., Ebert W., Elste V., Semmler W., Taupitz M. Gaida J., Herrmann A., Ebert M., Swiderski U., U.S. Pat. 20030185757; S. Palmacci, L. Josephson, U.S. Pat. No. 5,262,176; R. S. Molday, U.S. Pat. No. 4,452,773; Palmacci, S., Josephson, L., and Groman, E. V., Patent WO/1995/005669]. Thus, simpler, faster, practical, and non-tedious strategies to effectively produce monodisperse magnetic metal oxide nanocolloids are needed.
In view of the foregoing, the objective of the present invention is to provide a safer, simpler, efficient, scalable, and economical method of producing narrow-sized iron-based colloidal nanoparticles.